cgp_async_macro/
lib.rs

1#![no_std]
2
3/*!
4   This library provides helper macros for using async functions in traits.
5*/
6
7extern crate alloc;
8extern crate proc_macro;
9
10use proc_macro::TokenStream;
11
12mod impl_async;
13
14/**
15    The `#[async_trait]` macro is used to desugar async functions in traits
16    to return `impl Future`.
17
18    This macro is required mainly to get around the current limitation of
19    [async functions in traits](https://blog.rust-lang.org/2023/12/21/async-fn-rpit-in-traits/),
20    which would produce a lint warning for `async_fn_in_trait` if bare async
21    functions are defined in a trait.
22
23    ## Example
24
25    Given the following trait definition:
26
27    ```rust,ignore
28    #[async_trait]
29    pub trait CanRun {
30        async fn run(&self);
31    }
32    ```
33
34    The macro would desugar it to the following:
35
36    ```rust,ignore
37    pub trait CanRun {
38        fn run(&self) -> impl Future<Output = ()>;
39    }
40    ```
41*/
42#[proc_macro_attribute]
43pub fn async_trait(_attr: TokenStream, stream: TokenStream) -> TokenStream {
44    impl_async::impl_async(stream.into()).into()
45}
cgp_async_macro/lib.rs

cgp_async_macro/
lib.rs
